1116.  Before concluding, I may briefly remark, that on using a voltaic battery of fifty pairs of plates instead of a single pair (1052.), the effects were exactly of the same kind.  The spark on making contact, for the reasons before given, was very small (1101. 1107.); that on breaking contact, very excellent and brilliant.  The continuous discharge did not seem altered in character, whether a short wire or the powerful electro-magnet were used as a connecting discharger.

1117.  The effects produced at the commencement and end of a current, (which are separated by an interval of time when that current is supplied from a voltaic apparatus,) must occur at the same moment when a common electric discharge is passed through a long wire.  Whether, if happening accurately at the same moment, they would entirely neutralize each other, or whether they would not still give some definite peculiarity to the discharge, is a matter remaining to be examined; but it is very probable that the peculiar character and pungency of sparks drawn from a long wire depend in part upon the increased intensity given at the termination of the discharge by the inductive action then occurring.

1118.  In the wire of the helix of magneto-electric machines, (as, for instance, in Mr. Saxton’s beautiful arrangement,) an important influence of these principles of action is evidently shown.  From the construction of the apparatus the current is permitted to move in a complete metallic circuit of great length during the first instants of its formation:  it gradually rises in strength, and is then suddenly stopped by the breaking of the metallic circuit; and thus great intensity is given by induction to the electricity, which at that moment passes (1064. 1060.).  This intensity is not only shown by the brilliancy of the spark and the strength of the shock, but also by the necessity which has been experienced of well-insulating the convolutions of the helix, in which the current is formed:  and it gives to the current a force at these moments very far above that which the apparatus could produce if the principle which forms the subject of this paper were not called into play.

Royal Institution, December 8th, 1834.

TENTH SERIES.

S 16. On an improved form of the Voltaic Battery. S 17. Some practical results respecting the construction and use of the Voltaic Battery.

Received June 16,—­Read June 18, 1835.

1119.  I Have lately had occasion to examine the voltaic trough practically, with a view to improvements in its construction and use; and though I do not pretend that the results have anything like the importance which attaches to the discovery of a new law or principle, I still think they are valuable, and may therefore, if briefly told, and in connexion with former papers, be worthy the approbation of the Royal Society.